Scientists crack DNA code of rice

Advancement may help produce new varieties

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NEW YORK — An international team of scientists has deciphered the genetic code of rice, an advance that should speed improvements in a crop that feeds more than half the world's population.

It's the first crop plant to have its genome sequenced, which means scientists identified virtually all the 389 million chemical building blocks of its DNA. Certain sequences of these building blocks form genes, like letters spelling words.

The advance will help breeders produce new rice varieties with traits such as higher yield, improved nutritional content and better resistance to disease and pests, said one of the project's leaders, W. Richard McCombie of Cold Spring Harbor Laboratory in New York.

"I would think this is going to help people find genes and probably enhance the crop in well under 10 years," McCombie said.

The work is reported in Thursday's issue of the journal Nature by the International Rice Genome Sequencing Project, which was established in 1998 and includes scientists from 10 nations. The effort was led by Japanese researchers.

In the Nature report, scientists estimated rice contains 37,544 genes but said that figure will no doubt be revised with further research. Humans, by contrast, have only 20,000 to 25,000 genes.

They also said having the genome sequence in hand will be crucial for breeding and biotechnology advances to increase rice yield, noting that by one estimate the world's rice production must increase by 30 percent over the next 20 years to keep up with demand.

Besides Japan and the United States, participating scientists came from Brazil, China, France, India, Korea, Taiwan, Thailand and the United Kingdom.

Pamela Ronald of the University of California, Davis, who studies disease resistance in rice but didn't participate in the project, said the sequencing of the rice genome lets scientists do new experiments to unlock secrets of the plant.

"A lot of people are building on this work," she said.

For example, her laboratory used data released earlier from the sequencing project to develop a way to identify rice genes that become active when the plant deals with stresses like a germ attack or drought. That can help scientists track down particular genes for targeting in breeding programs, she said.